Re: [Xen-devel] [PATCH] introduce grant copy for user land

[Thanos Makatos <thanos.makatos@xxxxxxxxxx>]

> >> We also don't want multi-page allocations in this driver, so the
> >> batch size should be set accordingly.
> >
> > Why not?
> 
> Multi-page allocations are more likely to fail because of memory
> fragmentation.

Since we're keeping the alignment restriction, the code stays pretty much the 
same. Therefore what we need is to
pick the correct value for GNTDEV_GRANT_COPY_MAX_OPS such that sizeof(struct 
gcopy_cb) < PAGE_SIZE, correct?

> >> The interface should also support grant to grant copies.
> >
> > To support grant to grant copies, struct gntdev_grant_copy_segment
> > will have to contain an additional set of grant refs, correct?
> 
> The hypervisor ABI uses a union of handle and grant ref.  Perhaps something
> similar for the kernel interface?

Indeed, this is what I had in mind.

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